1. Field of the Invention
The present invention pertains to trailer hitches, and in particular to trailer hitches having guide walls surrounding the coupling between the trailer and a vehicle which pulls the trailer.
2. Description of the Prior Art
Many trailer hitches today use a well-known type of hitch apparatus wherein a socket on the tongue of the trailer engages a ball joint of standard size, which is mounted to the towing vehicle. Several improvements have been made to a simple ball joint mounted to a bumper. For example, U.S. Pat. Nos. 4,417,748; 4,226,438; and 3,420,549 disclose upstanding wall members partially surrounding the ball joint which act as a guide for directing the tongue of the trailer to the ball joint during a coupling operation. In addition, U.S. Pat. No. 4,417,748 provides a swivel mounting for the trailer hitch guide which follows movement of the trailer tongue as the trailer is pulled by a towing vehicle. Also included is a pin-like locking member which prohibits swiveling of the hitch guide when the pin is advanced to engage the bumper of the towing vehicle.
However, none of the aforementioned patents provide a much-needed lock for the coupling between a trailer and a towing vehicle, such as the locking arrangement shown in U.S. Pat. No. 3,522,958. The locking arrangement includes an L-bracket overlying the tongue of the trailer to prevent upward motion thereof which would result in an uncoupling with the ball joint. This locking arrangement is, however, cumbersome, involving specially-made parts which require additional assembly operations beyond that associated with coupling the trailer tongue and ball joint.
In addition to bumper-mounted hitches, hitches are sometimes provided in the bed of a truck. U.S. Pat. No. 4,183,548 discloses such an arrangement wherein a ball joint is attached to a sliding coupling, which in turn is received in a slotted plate mounted to the bed of a truck. Such arrangements are, however, unsuitable for smaller-sized trailer towed by passenger cars and the like vehicles. While a locking arrangement is provided for the intermediate ball coupling assembly, no locking is provided for the trailer coupled to the ball joint.
Sometimes, it is desirable to deter the theft of a trailer, accomplished by attaching a trailer to an authorized vehicle for its subsequent. U.S. Pat. No. 3,884,055 provides a theft deterrent in the form of a locking device including a U-shaped shackle, a plug to be received in the socket of a trailer hitch, and a pin overlying the plug and secured to the shackle. When inserted in the shackle, the free end of the pin receives a padlock to prevent its extraction. In effect, the locking arrangement is locked to the socket of the trailer with the plug member obstructing entry into the socket which is necessary for coupling to a ball joint.